Alfred l



UNITED STATES .PTENT oFFIcE.

ALFRED L. BROADBEN '1 AND RICHARD G. WbOD'BRIDGE, JR, WIIIMINGTON, .DELA- WARE, ASSIGNORS T0 E. I. DU PONT DE NEMOURS AND COMPANY, OF WILMINGTON, DELAWARE, A. CORPORATION OF DELAWARE.

PROCESS OF MAKING PROPELLENT POWDER.

1N0 Drawing.

character, and more partlcularly, however,

to the production of propellent powders of the progressive type, that is to say which are so treated as to provide a lower in1t1al pressure without reducing the velocity of the projectile. Our invention is applicable to the various kinds of rifle and cannon powders.

A further object is to provide a powder of this type which avoids the great disadvantage present in previous powders of this type due to the fact that said powder comprised coatings on the outside but not im-' pregnating the surface of the powder grain, thus rendering the powder vgrains so diflicult of ignition that hang-fires have resulted unless very strong primers were used.

A further object is to provide a process by means of which the surface of the powder grains may be effectively impregnated w th a deterrent in such a manner that the grams are prevented from adhering to each other, and to obtain a more uniform impregnation of the grain by the coating than has heretofore been obtained.

ment inmany difierent forms, for the purpose of illustration we shall describe only one process indicating the manner in which our invention may be carried out.

For example, we may proceedv as follows:

Nitrocellulose powder grains are provlded with a coating of a deterrent ex losive, such as a nitrohydrocarbon, but pre 'erably, by dinitrotoluene, as, for example, the 1, 2, 4 isomere (c. p. dinitrotoluene), although the mixture of dinitrotoluene as obtained by the'direct-nitration of toluol may be used. This coating may be appliedin the following manner, for example:

The dinitrotoluene may be dissolved in a suitable solvent, as for example benzol, to give a practically saturated solution. The

benzol need not be the pure article but may I While our invention is capable of embodi- Specification of Letters Patent. Patented Aug. 19, 1919-- Application filed July 14, 1916. SerialNo. 109,249.

be the usual commercial grade. The solution of the dinitrotoluene in benzol is made practlcally saturated simply to save solvent.

This solution is sprayed on the powder while the grains are stirred over and over. The solvent may be evaporated as by means of an air blast, leaving the powder grains coated on the surface with the dinitrotoluene. However, we prefer to use the following practice. Instead of dissolving the dinitrotoluene in the-benzol and spraying on, this solution, we prefer to mix the dinitrotoluene with the grains of powder and then thoroughly wet the powder with the.

benzol. The amount of benzol required is very much less than that required to completely dissolve the dinitrotoluene. The powder grains are then turned over and over as by revolving the drum orcontainer, and the solvent action of the benzol on the dinitrotoluene is such that within a .half hour to an hour, the crystals of dinitrotoluene have practically disappeared. The benzol is then evaporated as by means of an airblast and the powder is found to be coated on the surface with the dinitrotoluene. Or the coating material may be applied in the form of a dry powder by the use of a tumbling barrel, in which the nitrocellulose powder grains and the dinitrotoluene 1n the form of a dry powder are ,mixed and subjected to the actionof heat sufficient to melt the coating material and cause itto adhere to the powder grains.

The powder grains when coated in this manner are very difiicult of ignition, if they are not subjected to the following further treatment, in accordance with our invention: After the powder grains have been provided with the coating of dinitrotoluene, as above, they are immersed in hot water, preferably at a-temperature of from 40 to- 70 (3., depending upon the melting point of the coating compound used. However, it is not necessary to raise the temperature to the melting point of the coatingmaterial, because it is sufliciently softened to penetrate the surface of the grams at a temperature somewhat below the meltin point. The most advantageous temperature is from to 65 C. for the water bath in which the grains are immersed, although the .true 7 tained in the bath of hot water for a period of from several hours to several days, but we have found that usually one day is sufficient. The treatment by the hot water causes the deterrent explosive to be absorbed by the powder grains so that while the deterrent explosive is concentrated near the surface of the powder grains it penetrates into the same for a considerable depth, so that in the burning of the powder the successively exposed surfaces contain less and less of the deterrent explosive, thus causing the combustion to proceed with increasing rapidity. We have found that a charge of 39.6 grains of colloided nitrocellulose rifle powder, after having been provided with a coating as above described, and dried and glazed with graphite, and without having been subjected to the water treatment, gives a velocity of 24:20 feetto a second, and a mean pressure of 48,800 lbs. per square inch. A sample of the same powder, after having been subjected to the water treatment at 60 C. for about fifteen hours, and then dried, when tested with the same rifle, gives the same velocity, but with a mean pressure of only 43,300 lbs.

The hot water performs the functions of applying heatto the coated grains and acting as a medium to keep the grains from adhering to each other. This it does because it is both an agent for applying heat and a fluid which is not a solvent of the coating or of the powder; The two functions might, of course, be separately performed.

While we have described our invention above in detail, we wish it to be understood that many changes may be made therein without departing from the spirit of our invention.

We claim:

1. The process of impregnating the surface of an explosive grain insoluble in water with a deterrent material substantially nating the surface of an explosive grain 1nsoluble in water with a dinitrotoluene by subjecting the grain, coated with said dinitrotoluene, to treatment with hot water.

4. The process which comprises impregnating the surface of an explosive grain insoluble in water with a substantially pure 1-2-4 dinitrotoluene by subjecting the grain, coated with said substantially pure 1-2-4 dinitrotoluene, to treatment with hot water."

'5. The process which comprises impregnating the surface of an explosive grain insoluble in Water with a dinitrotoluene by subjecting the grains intimately mixed with said dinitrotoluene, totreatment with hot water.

6. The process which comp-rises impregnating the surface of an explosive grain insoluble in water with substantially pure 1-2-4 dinitrotoluene by subjecting the grains,

intimately mixed with said substantially pure 1-2-4: dinitrotoluene, to treatment with hot water.

7. The process which comprises impregnating the surface of an explosive grain insoluble in water with a deterrent material substantially insoluble in water'by subjecting the grains, intimately mixed with the said. deterrent material, to treatment with. hot water.

8. The process which comprises impregnating the surface of an explosive grain in soluble in water with a deterrent explosive substantially insoluble in water by subjecting the grains, intimately mixed with the said deterrent explosive, to treatment with hot water.

9. The process which comprises impregnating the surface of an explosive grain insoluble in water with a deterrent material substantially insoluble in water by subjecting the grain, coated with said deterrent material, to treatment with hot water at a temperature below the 1nelting point of the coating material.

10.' The process which comprises impregnating the surface of an explosive grain insoluble in water with a deterrent explosive substantially insoluble in water by subjecting the grain, coated with said deterrent explosive, to treatment with hot water at a temperature below the melting point of the coating material. A

11..The process which comprises impregnating'the surface of an explosive grain insoluble in water with a dinitrotoluene by subjecting the grain, coated with said dinitrotoluene, to treatment with hot water at a temperature below the melting point of the coating material. I i

12. The'process which comprises impregnating the surface of an explosive 'grain insoluble in water with a substantially pure 1-2-4 dinitrotoluene, by subjecting the grain, coated with said dinitrotoluene, to treatment with hot water, at a temperature beluv; the melting point of the coating mater1a 13. The process which comprises impregnating the surface of a nitrocellulose powder grain with a deterrent material substantially insoluble in water by subjecting the grain, coated with said deterrent material, to treatment with hot water.

14. The process which comprises impregnating the surface of a nitrocellulose powder grain with a deterrent explosive substantially insoluble in water by subjecting the grain, coated with said deterrent explosive, to treatment with hot water.

15. The process which comprises impregnating the surface of a nitrocellulose powder grain with a dinitrotoluene by subjecting the grain, coated with said dinitrotoluene, to treatment with hot water.

16. The process which comprises impregnating the surface of a nitrocellulose powdergrain with a substantially pure 1-2-4: dinitrotoluene by subjecting the grain, coated with said substantially pure 1-2-4 dinitrotoluene, to-treatment with .hot water.

17. The process which comprises impregnating the surface of a nitrocellulose powder grain with a deterrent material substantially insoluble in water by subjecting the grain, coated with said deterrentmaterial, to treatment with hot water at a temperature below the melting point of the coating material.

18. The process which comprises impregnating the surface of a nitrocellulose powder grain with a deterrent explosive substantially insoluble in water by subjecting the grain, coated with said deterrent explosive, to treatment with hot water at a temperature below the melting point of the coating material.

19. The process of impregnating the surface of powder grains with a deterrent material insoluble in water, while preventing the grains from adhering, comprising subj ecting powder grains coated with the deterrent material to a treatment with hot water.

20. The process of impregnating the surface of powder grains with a deterrent material, while preventing the grains from adhering, comprising subjecting powder grains coated with a deterrent explosive material substantially insoluble in water to a.treatment with Water heated below the melting point of the coating material.

21. The process which comprises coating a powder grain with a deterrent material, subjecting the coated grain to an inert liquid heating medium to melt the deterrent material and maintaining the coated grain in contact with said heating medium until the deterrent material has substantially impregnated the grain.

22. The process which comprises coating a powder grain with a deterrent explosive,

subjecting the coated grain to an inert liquid heating medium to melt the deterrent explosive, and maintaining the coated grain in contact with said heating medium until the deterrent explosive has substantially impregnated the grain.

23. The processwhich comprises coating a powder grain with a dinitrotoluene, subjecting the coated grain to an inert liquid heating medium'to melt the dinitrotoluene,

.- coated grain in. contact with said heating medium until the dinitrotoluene has substantially impregnated the grain.

25. The process of impregnating the surface of explosive powder grains with a deterrent material which comp-rises agitating the powder grains in the presence of the deterrent material and a volatile solvent of the deterrent material, evaporatin the solvent 'to leave a coating on the grains, and subjecting the resulting coated grains to water sufficiently hot to melt the coating.

26. The process which comprises coating and impregnating the surface of explosive grains with a deterrent material, and subjecting the coated grains to the action .of

27. The process which comprises coating and impregnating the surface of explosive powder grains with a deterrent explosive, and subjecting the grains to the action of heat and a liquidwhich is not a substantial solvent of the coating or of the powder. 28. The process which comprises coating and impregnating the surface of a nitrocellu-v lose powder grain with a dinitrotoluene, and subjecting the coated grains to the action of heat and of a liquid medium to keep the grains from adhering to each other.

29. The process which comprises coating and impregnating the surface of a nitrocellulose powder grain with a substantially pure 1-2-4 dinitrotoluene, and subjecting the grains to the action of heat and of a liquid medium which is not a substantial solvent of the coating or of the powder.

30. That step in the process of impregnating the surface of an explosive powder grain with a deterrent material comprising agitating .the powder grainin the presence of a dry deterrent material and adding a less quantity of volatile solvent than will form a saturated solution of the deterrent material and evaporating the solvent to leave a coating on the grain.

31. That step in the process of impregnating the surface of an explosive powder grain with dinitrotoluene comp-rising agitating the powder grain in the presence of dinitrotoluene and benzol and evaporating the benzol to leave a coating of dinitrotoluene on the powder grain.

32. That step in the process of impregnating the surface of an explosive powder grain with dinitrotoluene comprising agitating the heat and a liquid mediumto keep the grains from adhering to each other.

powder grain in the presence of dinitrotol- Castle, State of Deleware, on the days and uene and b-enzol in a less quantity than is dates opposite our names Written. gecessary1 to for m a saturated solution of the I ALFRED L. BROADBENT July 7,1916% lnltloto rt evapommng o RICHARD G.WO0D'BRIDGE,JR. Ju1 7 1916. to leave a dlnltrotoluene coatlng on the grain. Witnesses In testimony whereof e have hereunto A. M. GORMAN, set our hands at Wilmington, county of New P. E. STRIGKLAND. 

